Around 84% of the world’s coral reef areas had been affected by mass bleaching

On April 23, the International Coral Reef Initiative reported that about 84% of the world’s coral reef areas have been impacted by mass bleaching caused by abnormally high ocean temperatures over the past year.

• This marks the fourth global coral bleaching event since 1998 and has now exceeded the extent of bleaching during 2014–2017, which affected about two-thirds of reefs.

• Global mass bleaching of coral reefs is when significant coral bleaching is confirmed in the Atlantic, Indian and Pacific oceans

What are corals?

• Corals are sessile animals that permanently attach to the ocean floor, using tiny tentacles to catch food.

• Each coral animal is called a polyp, and large groups of genetically identical polyps form a colony. Corals are mainly divided into hard corals (which build reef structures) and soft corals.

• Coral reefs are vital ecosystems, often referred to as the “rainforests of the sea”, supporting about 25% of all marine species. For example, Australia’s Great Barrier Reef hosts over 400 coral species, 1,500 fish species, 4,000 mollusc species, and six out of seven sea turtle species globally.

• Corals have a symbiotic relationship with microscopic algae called zooxanthellae. These algae live inside coral tissues, providing oxygen and the products of photosynthesis that help corals grow, while corals offer them shelter. Zooxanthellae also give corals their bright colors.

Coral Bleaching

• Corals are highly sensitive to temperature and light. When stressed, they expel zooxanthellae, leading to coral bleaching — corals turn completely white.

• While bleaching doesn’t instantly kill corals, it weakens them, reduces their reproduction, and increases vulnerability to diseases. If conditions improve quickly, some corals can recover from bleaching.

(Source: IE)